Fluorescent lighting system



Patented Apr. 20, 1948 FLUORESCENT LIGHTING SYSTEM Charles P. Boucher and Russell W. Keiser, At-

lanta, Ga., assignors to Boucher and Keiser Company, Atlanta, Ga., a partnership Application April 25, 1944, Serial No. 532,682

Claims. 1

This invention relates to lighting system and more particularly to systems for the starting and operation of fluorescent lamps in groups of two or more.

It is a general object of the present invention to provide a novel and improved system and associated apparatus for the starting and operation of fluorescent lamps wherein the normal operation associates two or more lamps in series across the source of operating potential.

More particularly, it is an object of the invention to provide a system of and apparatus for operating two or more fluorescent lamps in series with provision for starting the first lamp in the series alone and by the cold cathode instantaneous method and the remainder of the lamps sequentially and by the hot cathode method.

A further object of the invention consists in the provision of a reactor and other accessory equipment for fluorescent lamp operation which provides full operating eificiency when combined with lamps varying in number from two to six.

An important feature of the invention comprises the arrangement of a ballast or reactor so designed as to require but one type thereof per lamp type, irrespective of the avaliable service voltages.

Another important feature of the invention consists in the provision of ballasts, one type for each type of lamp, all of the same style and physical size whereby they are interchangeable on a mounting or fixture and are independent of the servicing voltage, insofar as size and mounting is concerned.

A further important feature of the invention consists in the arrangement of a circuit for, minimizing the number of starting switches and their servicing costs.

Other and further features and objects of the invention, including the reducing of power losses; the minimizing of equipment; reduction in cost and amount of material required, will be more apparent to those skilled in the art upon a consideration of the accompanying drawing and a the following specification wherein is disclosed a single exemplary embodiment of the invention with certain variations such as fall within the scope of the appended claims.

In said drawing, the single figure is a diagrammatic and schematic representation of a system and apparatus for the starting and operation of from two to four fluorescent lamps from any available source of voltage, alternative sources being illustrated as connectable to the circuit by dotted lines.

most economical for general usage.

The development of fluorescent lighting, which had its inception in this country at the time of the New York Worlds Fair, has been rather haphazard. The standards of voltage, wattage, lamp lengths and diameters and other controlling factors largely followed from this experimental development, although of course some additional sizes have been added to the line. Operating voltages bear no logical relation to lamp size or wattage, and on the whole the picture is not very harmonious. This has resulted in uneconomical requirements for accessory equipment. Heretofore a separate ballast was required for each wattage lamp for each operating voltage available.

In this country the most popular alternating current voltages available may be divided into several groups, the first including 110, 115, 120, and the second 220, 230 and 250. In the third, 330 and 350 are included. These groups are followed by single nominal voltages 440 to 450, 550 to 575 and 600 to 660. Industry tentatively selected the 550 to 575 group as the best source for power but here lately the swing has been toward 440 to 450 volts and the latter value now tends to supersede all others for distribution and commercial service on account of its flexibility and the reasonable cost of static transformers, induction motors, switches and other equipment. Furthermore, it is readily divisible into two 220-225 volt circuits for operation of cheap single-phase motors and also into '110-112 volt incandescent lighting circuits. It further has the advantage of being well under the 600 volt limit applied by the underwriters for low voltage circuits and for which all ordinary circuit conductors have their insulation calibrated.

The system of the present invention is primarily designed for use with 440 volt circuits, and for the sake of simplicity, will be explained specifically in connection with the standard 40 watt fluorescent lamp which 'at the present is the Naturally the system and equipment can be adapted to most any commercial voltage and lamp size.

Present day practice requires the operation of fluorescent lamps with accessory equipment de signed for the voltage available where these lamps are in use. For instance, the conventional 40 watt lamp requires approximately 0.41 ampere as a normal operating current with 200 volts minimum operating potential. Two hundred thirty volts is a suitable operating potential, while from 380 to 450 volts are required for striking the are by the cold cathode method.

Thus it will be seen that on 110 volt circuits auto-transformers are necessary to provide the higher operating voltage and suitable reactors must be provided to limit the current. If the lamps are to be operated on some other voltage source different accessories are essential.

It has been initially accepted that fluorescent lamps are best when operated in dephased pairsto reduce cyclic flicker and stroboscopiczeffects from moving machinery, fans and the like, and second, to permit the improvement of power facttor of the system without unduly increasing. the. cost of equipment. The lighting industry has also accepted the hot cathode method" of starting. on account of the minimum requirements: in transformer and reactor equipment for'the operation of the type of lamps available. It. has become a general procedure to construct ballasts which are self-contained to operate lamps: in. pairs, and this method has the advantage of flexibility but has the following disadvantages. First, it. requires as many: ballast. designs as thereare available. voltages; second; it requires a multi plicity o1 mountingtemplets andfluorescent fixtures. made to operate at. certainprimary volt-- ages; third, it requires one. starting switch per lamp. and switch upkeep is costly; fourth, in. many cases it requires. a duplication. ofvoltage step-up equipment in the form of oneauto-trans former per pair of lamps; fifth, it multiplies-the causes of losses in voltagetransformation.

In contrast. tothe above, thepresent system provides the following. advantages. First, one ballast design per type of lamp. insteadof one ballast per type of lamp per voltage available; second, one mounting templet per. type of. lamp irrespectiveof. service voltage; third, aminimumof. starting switches; fourth, a minimum'of transforming equipment andlosses; fifth, lower manufacturing cost; sixth, less material used; seventh, less duplication of stock; eighth, less servicing.

To accomplish the above the present invention.

proposesthe construction of;one.ballast.unit only for each type of lamp and which. is-capable of operating two, three or four lamps of. that type.

Referring. now. to. the drawing, there isshown: at ill a source-of HO-volt alternating current. At I 2 is illustrated a dual reactor or ballast comprising leading winding [4. and lagging winding L6, preferably both wound on a. single core. of the closedmagnetic circuit type provided with suit.- able air gaps as particularly defined in the co.- pending application of. Russell. W. Keiser for Reactances, Serial. No. 445,047,.filed May 29, 1942. which issued October 30,- 1945, as-.United.States. Patent Number 2,387,797.. The. source I iscom nectedv through a. main switch, 11. to the center. point l8 of this reactor.

The lamps to be-operated are. shown as of: the conventional hot cathodetypeand. are numbered respectively 20, 2.1 22\ and.23. the point 2.5. on reactor winding iii a conductor. 26 conveys current. to both ends. of. thefllament. 28. of lamp.

20, these. being connectedtogether by a. suitable typeof. socket presently" available. The. opposite.

4 of this filament is connected to point 40 from which a conductor 4| leads back to the other side of the source of power Hi.

It will be seen that lamps 26 and H are in series so that when the switch H is closed, substantially 440 volts is applied between the filaments 28 and 30 of lamp 20. The remainder of the circuit is full metallic since lamp 2;! is shunted by si, and. this potential, which is adequate for cold starting of the lamp, strikes between the two filaments instantaneously and produces the are necessary to provide the illumination in the lamp. The current which immediately begins to flow is maintained at adesired value by the normal onerationofreactorwinding It. This current is further restricted in value since it flows through thetwo. filaments 33 and 36 of lamp 2i connected in series. This current now illuminating lamp 20;is sufficient to heat the filaments 33 and 35 to incandescence. Shortly after they are heated, switch S1 in its normal manner opens, breaking the filament circuits and placing the column of lamp'zi inseries with lamp 2B. The second lamp instantly strikes and normal operation commences with the two lamps in-series with the reactor, whichv now maintains the current at ap proximately 0.41 ampere as required, the two.

lamps dividing the voltage difference between 440 volts and that absorbed in the reactor equally between themselves for normal operation.

The leading half of the circuit is substantially identical with thelagging half as described, except that. the full winding i4 is used and the power. factor correcting condenser 4 1 is arranged.

in. series. therewith. and. with. the two. lamps. These two lamps are connected exactly as described in connection with the first pair and. the starting of the second. one of this pair is controlledby star-ting, switch S2. It will thereforebe seen that one starting. switch is sufficient for thetwo lamps.

In case. it isv desired to operate but two lamps in a fixture or from the reactor. l2, those connected to. the lagging side of the. reactor may be omitted, although it is preferred to use the method to be later described.

If it is desired to operate but three lamps,

one of the starting switch controlled lamps, for instance 2|,v is omitted, which necessitates the transfer. of. conductor 26 to point $5 on reactor winding l6. Wire 3| is omitted and replaced by dottedlineconductor 41 so thatlamp 21! operates purely as a cold. cathode starting, lamp in series. with the full number of turns on lagging winding. l6.

Where two. lamps are to be. used instead of. four and. witha minimum. of stroboscopic effects, lamp 22, as well as 2|, is removed and conductor 48.. substituted for 50 to. place. lamp 23in. series. with leading reactor winding M in thesame manner as lamp 20 was. placed in series. with the lagging reactor winding [6. described above.

Ithas been. demonstrated by.carefi1l tests that when. a winding such as. M. andiits condenser 44 are matched to operateone lampby thecold oath.- ode striking meth0d,.they. will operate two. lamps in series as well and without loss of efficiency or any appreciable change in the. operating characteristics of. the. two: lamps. This, means. that no destructive currentswill be usedtostart the first lamp, particularly when it is appreciated that the two filaments of. the hot cathode start ing lamp are. connected in. series with it. when it startscold. This appreciably lenghens the life of the cold cathode lamp even in the lagging. circuit and more appreciably in the leading one. The connections illustrated have been "tested at low voltage and low temperature, satisfactory results having been obtained at 0 centigrade and 380 volts at 60 cycles.

If two, three'or four lamps are associated with the dual reactor it operates at substantially its full capacity Furthermore, since 440 to 450 volts is the minimum R. M. 5. potential acceptable to strike 40 watt fluorescent lamps instantly, it will be recognized that the present method of operating these lamps requires the minimum amount of ballast material. One 440 volt 0.41 ampere reactor weighs about two pounds, depending to some extent on the design used which represents one pound per watt of ballast material for each lamp when four lamps are operated on a dual reactor. Compare this with approximately 2 pounds per lamp when they are operated from a 115 volt system.

In case 440 volts are not available from a source such as illustrated at In then any other source I0 may be used and connected through an appropriate auto-transformer 60 for either step-up or step-down operation. This transformer may be connected by conductors BI and 62 to the lines 53 and 64 in lieu of source I ii. In any event added conductors B6 and 61 beyond the main switch I! may be used for further-groups of lamps each of these groups requiring its own reactor but no additional transformer or source of power.

Where a supplementary transformer is required, it is preferred to use a large one for a number of lamp groups rather than an individual transformer for each group. Thus a single one KVA auto-transformer will take the place of ten 100 kva. transformers and will not cost nearly as much. No duplication of distributing feeders is required nor of switching, fusing, grounding or the like, and one pair of number 14 wires in a BX cable will carry suiiicient current from the transformer for 100 40 watt lamps. Obviously. the overall loss with the large transformer will be much less than with a number of smaller ones. If any reactors need replacing in such a system, they can alone be removed without renewing auto-transformers which, in most cases, are now combined with them.

The system for starting and operating two lamps in series can be effectively carried out with an increased number of lamps so long as their combined operating voltages are no greater than the available potential for supplying them, Each lamp beyond the first, which strikes by the cold cathode method, will require a starting switch arranged in the manner illustrated in the drawing. It is not proposed to carry this increase in series much beyond three lamps for satisfactory operation.

The use of three lamps in series suggests the possibility of the standard 100 watt lamp used in that manner on a 440-volt circuit, since these lamps have a striking potential of about 375 volts and an operating potential of approximately 150 will be provided with identical bases. This will require the use of but a single style mounting templet or simpler still, will enable each manufacturer of fixtures to pre-punch them to receive the fastening for mounting the reactors. This greatly decreases the amount of labor necessary for assembling and installing the lamp equipment.

The system and apparatus as above described provides for emininetly satisfactory operation of standard fluorescent lamps with a minimum of equipment. A particular advantage resides in the instantaneous striking of one or two lamps in each fixture so that persons entering a darkened room and snapping the switch at the doorway have light available instantaneously in contrast with the required wait of as much as 30 seconds where hot cathode starting is used entirely.

We claim:

1. A fluorescent lamp system comprising in combination with a source of current having a voltage at least twice the operating potential of a lamp, of a pair of like fluorescent lamps, a reactor, and conductors associating the lamps and reactor in series with the said source, one of said lamps having its electrodes connected in said series for cold starting and the other having its electrodes connected in said series for heated cathode starting, a starting switch of the type having a closed circuit when cold connected to close the heater circuits of the second lamp whereby the first lamp starts instantly on closing the circuit, the second lamp starts when its switch opens and both lamps then operate in series.

=2. In combination, a plurality of gaseous electric discharge devices having therein spaced electrodes, the electrodes of all but one of said devices being thermionic and arranged to be heated by the passage of current therethrough prior to the starting of the devices, a ballasting reactor, means connecting the said devices and the reactor in a series circuit, and a separate time delay starting switch connected across each one of the devices having thermionic electrodes and in series with these electrodes whereby the one said device starts instantly by the cold cathode method followed. by the other devices as determined by the operation of their switches.

3. In combination, a source of alternating current, a pair of fluorescent lamps having therein spaced electrodes, the electrodes of one of said lamps being thermionic and arranged to be heated by the passage of current therethrough prior to the starting of the device, a ballasting reactor, means connecting the said lamps and the reactor in a series circuit and a time delay starting switch connected across the electrodes of only the lamp having the thermionic electrodes and in series with these electrodes, whereby the other lamp receives the full potential of the said source when first connected and starts instantly followed by the second lamp when its switch functions.

4. The combination claimed in claim 3 in which a dual ballasting reactor, means connecting said source, one side of said reactor and one group of said devices in a series circuit, means connecting said source, the other side of said reactor and the other group'of devices in a second series circuit, a separate time delay starting switch connected across each one of the devices having thermionic electrodes and in series with these electrodes, whereby the one device in each group starts instantly by the cold cathode method followed by the other devices as determined by the functioning of their switches.

6. The combination with a source of alternating current of two pairs of gaseous electric discharge lamps, one only of each pair having an electrode at each end thereof arranged to be heated by the passage of current therethrough prior to the starting'of a discharge in the lamp, the other lamp of each pair having an electrode at each end thereof arranged only for cold cathode starting, a ballasting reactor having two windings, means connecting said source, one of said windings and the two lamps of one pair in a full series circuit, means connecting the said source, the other of said windings and the two lamps of the other pair in a second full series circuit, a separate time delay starting switch across each one of the lamps having thermionic electrodes and in series with these electrodes whereby the lamp in each group which has no switch starts instantly and is followed by the switch controlled lamp.

7. The method of starting and operating fluorescent lamps in pairs comprising, connecting two lamps in series across a source of potential at least equal to twice the required operating potential for each lamp, shunting one lamp to start the other by the cold cathode method, causing said shunting to heat the electrodes of the shunted lamp, opening said shunt to start the second lamp and limiting the current flow during normal operation.

8; A system for starting and operating two to four standard 40 watt 48-inch fluorescent lamps requiring at least 200 volts each for operation and 440 volts for cold cathode starting comprising a source of 440 volts A. 0., a reactor including a leading winding with a series condenser and a lagging winding with an intermediate tap, means connecting two of said lamps into aseries circuit'with-each winding of said reactor and'said source, means independently and separately shunting the filaments of one lamp in each pair,

a time delay starting switch shunting the other lamp in each pair and when closed: conditioning the filaments to be heated, the tap on said-1eactor providing for proper'operation of two lamps in series and the full winding for proper cold cathode starting and normal operation of asingle lamp.

9. A system for operating six standard mil-watt 72-inch fluorescent lamps each requiring ap-- proximately volts for normal operation and 3'75 volts for cold cathode starting comprising a source of 440' volts A. 0 a reactor including: a leading winding with condenser and a magnetically coupled lagging winding, means connecting three lamp into a series circuit with each winding and the source, means independently shunting the filaments at each end of one lamp in each series, a separate time delay starting switch shunting the remaining lamps in each series when in closed condition and then conditioning the filaments to be heated by the current flowing in the first lamp when started cold;

10. The combination with a source of current supply, of a pair of fluorescent lamps connecting inseries with said source, one of said lamps be} ing arranged to start instantly when the" current is turned on, the other lamp having its fliaments connected in series and with the first lamp prior to starting whereby the current to the first lamp is limited thereby; means to automatically open the filament series without disrupting the lamp series and means to limit the operating. current for both lamps when operating normally.

CHARILESP. BOUCHER. RUSSELL 'W. KEISER'.

REFERENCES GITED The following references are ofrecord in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,025,471 Osborne Dec. 24', 1935' 2,056,661 Foulke Oct. 5, 1936- 2,125,799 Metcalf Aug. 2, 1938 2,241,261 Horn May 6, 1941 2,266,619 Campbell Dec. 16,1941 2,298,935 Freeman i Oct. 13, 1 943- 2,354,879 Rianney e 'Aug. 1, 1944 

